Childerns Account

Can anyone help me please!

My 10 year old is on his xbox with xbox live we bought him F1 25 with the idea of myself playing with him on my pc. He's playing it offline and online and I've tried to import him as a friend through me EA app and I get '' Couldn't send request ''

I thought I would log into his account put his email in and then his password and I get '' Your credentials are incorrect or have expired. Please try again or reset your password.'' I reset his password and I get them same again I don't understand what's going off what am I missing? 

Can anyone point me in the right direction please? We bought the game to race against each other and to make a team together seems a waste of money now! We both had F1 24 on my game pass and thought we couldn't play 24 because of that both using my xbox game pass. So that's why I bought the game through his own xbox account thinking that would work but no! 

Any help please?